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Sunday, 3 June 2012

Lovepedal Silicon Fuzzmaster

Request. This was traced from some pics and a PCB layout. It's a negative ground YAFF with PNP silicon transistors for some reason.

From the Lovepedal spiel:

Your quest for the ultimate Fuzz ends here.

Lots of players use it like an OD pedal or full on fuzz, even distortion.. Roll back the guitar's volume and you're left with a lively shimmer atop your guitar and amp's identity. Amazingly, this happens to an appropriate degree throughout the pedal's range, and without the annoyingly excessive boost in volume that many overdrive pedals generate. And, yes, it's dead quiet.

The Fuzzmaster is a VERY sweet, smooth, silicon transistor based, fuzz that is warm, organic and sings with sustain. While it has an UN-mistakable vintage tendency, it also has a unique voice. Vintage Fuzz Face tonal heaven and everything in between, even tweed amp tones are in there.

The traced schematic:

The last layout (Rev 2) seems to be fine so if you're building it don't worry, but it occurred to me that if I move a couple of the resistors around then I can save an extra column and so the following revised layout does that. In fact if you get rid of the completely unnecessary 100n filter cap at the bottom right hand side you could save another column as well. I'll leave that up to you though.

And a final compact version without the unnecessary 100n filter cap. Just build whichever one you like! :o)

Update: Schematic and layout now done from the corrected PCB layout. As an option try 33pf-47pf caps between collector and base on both transistors to help smooth things out.

74 comments:

G-D i, you are THE MAN! I will build it up a little later. I may make the board a little wider as to use a Bournes-type single-turn trimmer. The 125 enclosure I think does 21 or 22 wide!! Thanks and stay tuned!

Had a couple of hours with this. Swapped the trimmer with normal pot and wired it to the right edge strips 2, 3 and 4. Schematic and layout seem to match, but i can't get it working. Went it through with magnifying glass and knife, also i've reflown every joint to no avail. Also, went through every component and their location.

Closest moment was when i pressed transistors down to the sockets hard while pressing on the back side of the board. Can't even isolate what strips need to be connected to get any sound through it.+m

OK thanks for the feedback. I'll go over the PCB again but it looks pretty much like a slightly modded Fuzz Face layout to me, but with the supply and ground swapped round to accomodate the PNP transistors in a negative ground circuit and I can't see anything that would cause too many problems. Can you measure the pin voltages and email me a couple of pics?

Try adding the new link shown above and see if that helps. It wasn't in the PCB I traced but mictester on FSB thinks that it may have been a mistake which would have been corrected with a small external link wire on the back of the PCB.

1. The left pin/via for R4 should go the the bottom layer (ground).2. The top pin/via of C5 should go to the bottom layer (ground)3. The middle pin/via of TR1 (trimmer) should also connect to the top pin/via of TR1 and top pin/via of R3 (I think you guys already caught this one)4. The right pin/via of R8 that came from the right pin/via of R2, should connect to the negative terminal (top pin/via) of C1 and then onto the bottom pin/via of Q2.

Hopefully there is nothing else and we can finalize the schematic and stripboard!

I measured the following settings on the trimmer and transistors with 9V regulated power in and all pots turned fully counter-clockwise:

The stock setting of the 10k trimmer on the PCB layout is 2.73k

Q1:1 - 1.46V2 - 6.62v3 - 7.24V

Q2:1 - 6.62V2 - 7.48V3 - 7.93V

As indicated previously, yes, C1 (22uF) is connected directly to the transistor!

Yes, FF with some tonal/voicing changes and good output (well above nominal) and excellent fuzz characterists and versatility to tune in what one prefers, using PNPs (that I really think I can hear and superior to NPN's I've heard, and finally negative ground, so it doesn't mess with other pedals! Great design!!

It's late, but I went over the schematic. It looks rights. Only thing I would state is if you want 100% to the original design...C4 on the schamatic and layout need to be changed to electrolytic polarized caps with negative to VR2P3.

Likewise, personally I like using the Bournes trimmers, like the 3386P-1-103LF. I will probably go 20 wide like I did on the first revision and move everything after the second link to the right to allow space for the trimmer.

In the description, it is said that it uses positive ground, but in the layout it says 9V instead of -9V and you also said here "and finally negative ground", which leads me to belive that it is in fact negative groud thus, chainable with other pedals.

All the revised PCB did was add the link at the trimmer (which we'd already covered with that little link) and then connect the 100K from Q1 base, and the 1K connected to Drive 3 directly to Q2 emitter, and that wire should do exactly that. If it's working intermittently if you push on the transistor is suggests a bad joint somewhere to me. Maybe reflow the solder.

You're completely right, I came to the same conclusion so checked if I had all the components installed. I of course forgot the 33k resistor. I soldered it in and it worked immediately! Thanks! It's a pretty noisy circuit though but I guess that's just fuzz face! Could I put some BC108s in here?

No, that I was trying to say is the 100k-B blend pot (VR2) "P3" = Pin 3 or VR2P3 goes to C4 (1uF/50V electrolytic cap) and C4's negative terminal!!

I see IvIark updated it in the very latest schematic with polarity! :)

Anyone verify yet?? I'll start making the board and have all of the parts...except the pots and VR1 (1k-C "drive") pot. I have the parts on the way though. I need to de-populate the last board to recover the components and and make the knew board 2 columns wider to accept a Bournes-style trimmer (personally don't like multi-turn)., so it may be a couple days before I finish.

I'll have to measure them tonight. Can't remember. As a matter of fact, I have recently thought I might like to try some slightly higher gain ones from the lot that I ordered. I'll post back after I measure. I got kind of spoiled after I built the Skreddy P19 - so much thick gain. I still like this fuzzmaster a lot though.

On the trimmer, it's close to the middle of the trimmer. I just adjusted back and forth as I was playing until I got to a good sounding place ( very scientific, right? ). I'm still getting just a little bit of sputter on the back end of the decaying notes so I need to do a tad more adjusting. On mine, anywhere too far from that middle area (either way) of the trimmer sounded a bit nasty...

I pulled out the transistors that I had in there - they measured 247 and 255. I found one that was higher - 263 - so I put that back in with the 255. Not a big difference. Then for the heck of it, I found two that were close to each other of a lower value hfe - 208 and 212. After swapping back and forth a couple of times, I ended up settling on the lower gain pair. I seemed to be able to bias out that hiss and sputter better. I can play a chord and let it sustain without it sputtering out at the end of the decay ( well, mostly - it's still a fuzz...). And I really haven't noticed a tremendous loss of fuzz with the lower gain pair.

Hey Tim, thanks for the feedback. As the originals were not tested or pulled, I'm curious what's the best for this? I tried many combinations last week. What I found was as follows:

1. Yes, I like to have more gain on hand, so the higher the gain of both, the more available overall gain you have.2. Yes, I had the spuddering issue of decaying notes. This is solved by PAIRING matched gain transistors and using so-called "best" values - 80/120 or 120/150 and different transistors - Radio Shack, Fairchild, etc. I could not get gains that low to test the lower values, but like I said, the more separation in values..the WORSE, so keep 'em paired up and adjust gain level to taste, again, I like to have a lot on hand, so would tend for higher values than lower. Finally, all this trial and error, I have not messed with the trim pot much yet beyond setting to original voltage 1.46 or 2.xx (cold). Again, I have not set it at 4.5V and I don't think Love does either. There could be some "majic" in there also.

You know, I didn't think about the pairing aspect in this. I guess that's why places like Smallbear sell matched sets of transistors for Fuzzes. Looking at the lower values that I chose, I guess I'm liking them more because they're closer matched, so that sputtering issue is easier to tame.

It works! I like the fuzz alot. I should probably be satisfied that it works considering the luck I have had with my last few builds... but I am getting a lot of that fizzy decay. I might try the 47pf across C and B of the transistors but I really like high end in my pedals and I find the pf caps sometimes dull things. Has anyone else noticed any of the fizzy stuff I speak of?

Got the fizzles out with silver mica caps (never using ceramic again). Now it is my favorite fuzz. The blend is great. Any suggestions for a germanium in a similar flavor? I would strongly suggest silver caps between collector and base, and making room for them on your build!

I have question about the update, which I believe came from Gc66. How do I do this?...as an option try 33pf-47pf caps between collector and base on both transistors to help smooth things out.

Does this mean add a cap between Q1 Collector and Q2 Base (which I understand)? Or does it mean to add a cap between the Collector and Base of Q1 and then another cap between the Collector and Base of Q2? If it means the latter, how do I do this?

hello there i didn't make to trace a rev log pot all around Athens... Unfortunately i have all the pedal ready and the only i need is the pot... Is there a possibillity to make it without the rev pot in use of a lin or log pot?

Take 2k lin pot and solder an extra 2.2k resistor between lugs 2 & 3. That should be close enough. You can of course use 1K lin, but the sweep won't be as good as most of the usable range will be at the very end of the sweep.+m

built it, like it :)bought 100 2N3906's and all was in range of 330-350 :(i had hopes for some around 200 but NOOT.i biased Q2 collector to 2.5V, 1.3V sounded like the speaker got stabbed with a knifeand at 4.5V sound got very tight more like a overdrive and this is a fuzz build soi went for 2.5V.

it sounds just like the PGS demo where he plays nasty dogs and funky kingsand on same settings too :)

gonna try some lower gain transistors when i get some, Tayda is a cool place but not so much for trannys, but the other stuff is okey i guess....and real cheap :)

Maaaan! Just built this with a high gain germanium FF set 124/172hFE. 120p to tame Q1, 330p for Q2 a la DAM. External bias a la Sunface, 2k2 + 5kB pot. 500kC for volume pot. Now that's my favorite fuzz build and I've made quite a few so far. No worries for positive ground anymore, and high gain germaniums. Before boxing it might have a little his, (my OC42s had that) but in the box disappeared.

I think the better choice is 2N3906 as per original, I tried 2N3703 low gain with very poor results.My 2N3906 have hfe 248/298 and I used 47pf to tame both. Also I jampered the drive pot, it needs the guitar pot only :)Very cool and warm sound!

Hi. I’d tried two times this pedal, with the same problem. The first one, a pcb layout using the schematic above. The second, breadboarding using again this schematic. The same values for every component, checked one by one. When I put the drive pot to the max, appears a very loud noise. It’s between 95% and 100% of his position. The only common component used for both attempts was the C1k pot. I tried with a B1k, and the problem persisted.

A number of people have asked me to do a build guide for one of these effects, but I noticed the other day that one of the guys here (timmy)...

Note

Not all these layouts are verified and some are put together from unverified schematics. So if you have good luck, or bad luck for that matter, then please let me know by dropping a comment in the topic. Thanks.

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